KR20120098818A - Copper foil for secondary battery negative electrode power collector - Google Patents

Abstract

When the roughening process was performed on the front and back surfaces of the rolled copper alloy foil, the average surface roughness Ra by laser microscope measurement of the front and back surfaces was 0.04 to 0.20 µm, and the surface of the roughened surface was measured by a laser microscope. When the three-dimensional surface area of is set to (A) and the two-dimensional area of the projected area when the three-dimensional surface area is measured is set to (B), the calculated value of (A) / (B) = (C) (C) When the surface of the uncoated rolled copper foil and copper alloy foil was measured by a laser microscope, the three-dimensional surface area was determined as (A '), and the projection area when the three-dimensional surface area was measured was two-dimensional. When the area is set as (B '), the calculated value (C') of (A ') / (B') = (C ') is in the range of 1.0 <(C) / (C') <1.1. Copper foil for secondary battery negative electrode collectors characterized by the above-mentioned.
Copper foil for secondary battery negative electrode current collector which is excellent in the adhesiveness of a secondary battery active material, and can reduce the dispersion | variation in the weight thickness of a secondary battery active material, Furthermore, copper foil for secondary battery negative electrode collectors which is excellent also in weather resistance and heat resistance It is a subject to offer.

Description

Copper foil for secondary battery negative electrode current collector {COPPER FOIL FOR SECONDARY BATTERY NEGATIVE ELECTRODE POWER COLLECTOR}

The present invention relates to a copper foil for a secondary battery negative electrode current collector, and particularly, to provide a copper foil for a secondary battery negative electrode current collector that is excellent in adhesion to a secondary battery active material and can reduce variations in the weight thickness of the secondary battery active material. .

Copper and a copper alloy foil (henceforth a copper foil) greatly contribute to the development of the electric-electronic-related industry, and become indispensable as a printed circuit material and a secondary battery negative electrode collector. High adhesiveness with a resin base material and another material is calculated | required by copper foil, For example, in the case of the negative electrode electrical power collector for lithium secondary batteries, the adhesiveness of copper foil and a negative electrode active material is calculated | required. In order to improve the adhesiveness of the copper foil of a negative electrode collector and an active material, surface treatment which forms an unevenness | corrugation on the copper foil surface previously is generally performed, For example, a blasting process, rolling by a roughening roll, mechanical polishing, Methods such as formation of roughened particles (hereinafter referred to as roughening treatment) by electroplating using electropolishing, chemical polishing and electroplating using a copper sulfate plating bath are known, and among them, a roughening treatment is often used. The roughening process using a copper sulfate plating bath aims at the improvement of adhesiveness by anchor effect by electrodepositing copper particle on the copper foil surface, and forming an unevenness | corrugation. (For example, refer patent document 1 and patent document 2).

However, the roughened particle obtained by the copper sulfate plating bath had the problem that it was nonuniform and high roughness by accumulating the enlarged roughened particle. In other words, when the roughness of the roughened particles is high, on the contrary, the anchor effect is weakened, or the copper powder is dropped off at the portion where the roughened particles are accumulated, whereby sufficient adhesion between the negative electrode current collector copper foil and the active material is not obtained.

In the case of a lithium secondary battery, a carbon material is generally used as the negative electrode active material. In order to obtain a higher charge / discharge capacity, active materials in which silicon or the like has been thinned by a sputtering method or the like have also been studied. However, when silicon or the like is used as the negative electrode active material, the volume expansion and contraction due to lithium ion occlusion and release during charge and discharge cycles is large, causing the active material to peel off and drop off, resulting in a problem of deterioration of battery characteristics. Therefore, the improvement of the adhesiveness of an electrical power collector copper foil and an active material, and the fall prevention of the copper powder particle which a roughness buildup affects on the copper foil surface become an important subject.

Moreover, the height of the roughness by the roughening process particle | grains after performing a roughening process to copper foil, and the dispersion | variation in roughness will have a big influence on the formation amount of an active material. The amount of formation of this active material affects the electric capacity of the battery. Therefore, in order to form an active material uniformly on both front and back sides of copper foil, it is preferable that both the front and back sides after performing a roughening process to copper foil are the surface roughness of the same grade.

By the way, copper foil is roughly divided into electrolytic copper foil and rolled copper foil according to the manufacturing method. In general electrolytic copper foil, the rough surface side and the gloss surface side exist in the front and back. The rough surface side is a protrusion-like unevenness formed by the growth of columnar crystal grains peculiar to the electrolytic copper foil, and the gloss surface side is a shape formed by transfer of polishing traces of the electrolytic drum. Therefore, the surface shape of the front and back of the said electrolytic copper foil differs, and the roughness difference of the front and back becomes large. When the roughening treatment is performed on the front and back of the electrolytic copper foil, the roughness difference of the front and back is increased by reflecting the unevenness of the surface of the copper foil, and the variation in the roughness is also large, so that the uniformity of the amount of formation of the negative electrode active material described above is difficult. .

On the other hand, since a rolled copper foil hot-rolls an ingot and repeats cold rolling and annealing to predetermined thickness, and finally finishes thickness to 50 micrometers or less by final cold rolling, a rolled copper foil is manufactured, generally rolled copper The foil has a small roughness on both sides, and it is easy to reduce the roughness variation of the front and back surfaces. However, when the roughening process using the copper sulfate plating bath was performed on the rolled copper foil, the accumulation of the enlarged roughened particles was affected as mentioned above, and there existed a problem that the roughness became large and the variation of roughness became large.

Therefore, in order to improve active material adhesiveness, it is preferable to perform the fine roughening process which can achieve the roughness uniformity and the weight thickness uniformity to the front and back of the rolled copper foil, but it also has a limitation, and the balanced roughening process is needed, and the secondary It is the present situation that development is calculated | required as copper foil for battery negative electrode electrical power collectors.

Japanese Patent 3742144 Japanese Laid-Open Patent Publication 2002-319408

An object of this invention is to provide the copper foil for secondary battery negative electrode collectors which is excellent in the adhesiveness of a secondary battery active material, and can reduce the dispersion | variation in the weight thickness of a secondary battery active material.

The present invention,

1) A copper foil obtained by roughening the front and back surfaces of a rolled copper foil and a copper alloy foil, wherein the average surface roughness Ra by laser microscopy measurement of the front and back surfaces is 0.04 to 0.20 µm, and the surface of the roughened surface is lasered. When the three-dimensional surface area when measured under a microscope is set to (A), and the two-dimensional area of the projection area when the three-dimensional surface area is measured is set to (B), (A) / (B) = (C) When it is set as the calculated value (C), the three-dimensional surface area at the time of measuring the surface of the unprocessed rolled copper foil and copper alloy foil with a laser microscope is set to (A '), and when the three-dimensional surface area was measured. When the projected area two-dimensional area is set to (B '), the calculated value (C') of (A ') / (B') = (C ') is 1.0 <(C) / (C') < Copper foil for secondary battery negative electrode electrical power collectors characterized by the range of 1.1

2) The average diameter of the roughening particle | grains of a roughening process surface is 0.1-0.4 micrometers, Copper foil for secondary battery negative electrode electrical power collectors of 1) characterized by the above-mentioned.

3) The maximum height of a roughening process layer is 0.2 micrometer or less, Copper foil for secondary battery negative electrode electrical power collectors in any one of 1) -2) characterized by the above-mentioned.

4) The roughened particle is formed on the front and back surfaces of the rolled copper foil and the copper alloy foil by one kind of plating of copper, cobalt and nickel or by plating these two or more kinds of alloys. Copper foil for secondary battery negative electrode collectors described in thing

5) At least one antirust treatment layer or heat resistant layer selected from cobalt-nickel alloy plating layer, zinc-nickel alloy plating layer, chromate layer, and / or silane coupler on the roughened surface of both sides of the rolled copper foil and copper alloy foil. Copper foil for secondary battery negative electrode electrical power collectors in any one of 1) -4) characterized by having a ring layer.

6) The weight thickness deviation (sigma) of the copper foil width direction of the rolled copper foil and copper alloy foil after front-back both-side roughening process is 0.5 or less, The copper foil for secondary battery negative electrode collectors as described in 1) -5) is provided.

This invention is excellent in the adhesiveness of a secondary battery active material, and has the outstanding effect which can provide the copper foil for secondary battery negative electrode collectors which can reduce the dispersion | variation in the weight thickness of a secondary battery active material.

1 is a SEM photograph of roughened particles of a copper foil for a secondary battery negative electrode current collector of Example 1. FIG.
FIG. 2 is a cross-sectional FIB-SIM photograph of roughened particles of a copper foil for secondary battery negative electrode current collectors of Example 1. FIG.
3 is a SEM photograph of roughened particles of copper foil for a secondary battery negative electrode current collector of Comparative Example 1. FIG.
4 is a cross-sectional FIB-SIM photograph of roughened particles of a copper foil for secondary battery negative electrode current collectors of Comparative Example 1. FIG.

Copper foil used by this invention is a rolled copper foil and a copper alloy copper foil. Rolled copper foil and copper alloy foil are superior to electrolytic copper foil in high strength and bending resistance applications. When used as a negative electrode current collector of a lithium secondary battery, a thinner copper foil can obtain a higher capacity battery. However, when a thinner copper foil thickness is used, a risk of rupture due to a decrease in strength is generated. It is preferable to use the rolled copper foil and copper alloy foil which are more excellent in strength.

There is no restriction | limiting in particular in the kind of rolled copper foil and copper alloy foil used in this invention, It can select suitably according to a use and a required characteristic. For example, Cu-Ni-Si type copper alloy which added Sn containing copper, Ag containing copper, Ni, Si, etc. other than high purity copper (oxygen-free copper or tough pitch copper etc.), Cu, Zn, etc. Cu added Copper alloys, such as a -Cr-Zn system copper alloy, are mentioned.

The thickness of the rolled copper foil and the copper alloy foil is not particularly limited, and may be appropriately selected according to the use or required characteristics. Generally, when copper foil is used as an electrical power collector of a lithium secondary battery negative electrode, it is about 5-20 micrometers.

A roughening process is performed to both front and back of this rolled copper foil and copper alloy foil. And average surface roughness Ra by laser microscope measurement of the front and back both sides of this copper foil shall be 0.04-0.20 micrometer. In this sense, it can be said that surface roughness is very small compared with electrolytic copper foil.

The reason for setting the lower limit of the average surface roughness Ra to 0.04 µm is to form fine particles and to improve the adhesion of the secondary battery active material. As a result, the active material can be applied as much as possible, and the electric capacity of the battery can be increased. On the other hand, the reason for making an upper limit 0.20 micrometer is for reducing the variation of the weight thickness of a secondary battery active material. Thereby, the charge / discharge characteristic of a secondary battery can be improved.

Moreover, in this invention, the copper foil for secondary battery negative electrode electrical power collectors makes the three-dimensional surface area at the time of measuring the surface of a roughening process surface with a laser microscope as (A), and the projection area when measuring the three-dimensional surface area is measured. When the two-dimensional area was set to (B), when the calculated value (C) of (A) / (B) = (C) was used, the surface of the uncoated rolled copper foil and the copper alloy foil was measured by a laser microscope. When the three-dimensional surface area at the time is (A ') and the projected area two-dimensional area at the time of measuring the three-dimensional surface area is (B'), (A ') / (B') = (C ' ) Is in the range of 1.0 <(C) / (C ') <1.1. In order to improve the adhesiveness with a negative electrode active material and to improve the contact area with a negative electrode active material, and to raise an electric capacity of a battery, it is not enough only to make average surface roughness Ra into 0.04-0.20 micrometer.

In the present invention, it is important to manage (B) and (B ') the two-dimensional area of the projection area when the three-dimensional surface area is measured for (A) and (A') and the three-dimensional surface area. The two-dimensional area of this projection area refers to the area seen in plan. In this respect, (A) / (B) = (C) and (A ') / (B') = (C ') can be seen as the ratio between the solid and the plane. If this ratio (C) / (C ') is 1.0 or less, the adhesiveness of a battery active material will fall, and if (C) / (C') is 1.1 or more, the weight thickness of a secondary battery active material will generate | occur | produce, and battery characteristics will become It causes the deterioration (charge / discharge characteristics).

Thus, in this invention, it is set as the refinement | miniaturization process which can achieve uniformity of roughness and the uniformity of the weight thickness of an active material in the front and back of a rolled copper foil.

About the deviation of a secondary battery active material, when the thickness of 18 micrometers of copper foils differs in 0.5 micrometers in copper foil, 2.78% deviation arises with respect to copper foil thickness, for example. When apply | coating the active material of thickness 40micrometer to this copper foil, thickness deviation will correspond to 0.86% in the total thickness of copper foil and an active material. On the other hand, when the thickness variation of 18 micrometers of copper foil is made into 0.5%, when an active material of 40 micrometers in thickness is apply | coated similarly, the thickness variation will correspond to 0.155% in the total thickness of copper foil and an active material. From this, it can be seen that the thickness variation of the copper foil greatly affects the weight thickness variation of the secondary battery active material.

Moreover, it is preferable that the copper foil for secondary battery negative electrode collectors sets the average diameter of the roughening particle | grains of a roughening process surface to 0.1-0.4 micrometer. It is preferable that a roughening particle is a fine particle, and that the fine particle is more uniform. This is also a preferable form in order to improve the adhesiveness of a battery active material, apply | coat a large amount of an active material as much as mentioned above, and to raise the electric capacity of a battery.

This invention can manage based on the indicator which makes the average diameter of this roughening particle into 0.1-0.4 micrometer, and can achieve this.

Moreover, it is preferable that the copper foil for secondary battery negative electrode collectors sets the maximum height of a roughening process layer to 0.2 micrometer or less. This is also a preferable form in order to reduce the thickness variation of a roughening process layer, to improve the adhesiveness of a battery active material, to apply as many active materials as possible, and to raise the electric capacity of a battery.

This invention can manage based on the parameter | index which makes thickness of this roughening particle into 0.2 micrometer or less, and can achieve this.

Copper foil for secondary battery negative electrode electrical power collectors can form 1 type of plating of copper, cobalt, nickel, or these 2 or more types of alloy plating as a roughening particle. Usually, roughening particle | grains are formed by the triad alloy plating of copper, cobalt, and nickel.

Moreover, in order to improve heat resistance and weather resistance (corrosion resistance), the copper foil for secondary battery negative electrode electrical power collectors has a cobalt- nickel-alloy plating layer, a zinc- nickel-alloy plating layer, and chromate on the roughening process surface of both front and back of a rolled copper alloy foil. Forming at least one antirust or heat resistant layer and / or silane coupling layer selected from the layers is a preferred form of element.

By the above, the copper foil for secondary battery negative electrode collectors of this invention can make the thickness thickness deviation of the copper foil width direction of the rolled copper alloy foil after front and back double-side roughening process into 0.5% or less, and is excellent for secondary battery negative electrode collectors Copper foil can be provided.

The present invention a secondary battery negative electrode collector conditioner on the entire copper foil for processing, for example, copper-cobalt-?? will be described with respect to the nickel alloy plating, the, amount of deposition by the plating electrolyte 15 40 ㎎ / dm ² of copper -100 3000 It is performed to form a ternary alloy layer of μg / dm ² cobalt-100 to 500 μg / dm ² nickel. This ternary alloy layer is also equipped with heat resistance.

General baths and plating conditions for forming such ternary copper-cobalt-nickel alloy plating are as follows.

(Copper-cobalt-nickel alloy plating)

Cu: 10 ~ 20 g / ℓ

Co: 1 ~ 10 g / ℓ

Ni: 1-10 g / ℓ

pH: 1-4

Temperature: 30 ~ 50 ° C

Current density D _k : 20-50 A / dm ²

Time: 1? 5 seconds

The present invention can form a cobalt-nickel alloy plating layer on a roughened surface after the roughening treatment. The cobalt-nickel alloy plating layer has a cobalt adhesion amount of 200 to 3000 µg / dm ² and a cobalt ratio of 60 to 70 mass%. This treatment can be regarded as a kind of antirust treatment in a broad sense.

The conditions of the cobalt-nickel alloy plating are as follows.

(Cobalt-Nickel Alloy Plating)

Co: 1 ~ 20 g / ℓ

Ni: 1 ~ 20 g / ℓ

pH: 1.5? 3.5

Temperature: 30? 80 ° C

Current density D _k : 1.0-20.0 A / dm ²

Time: 0.5-4 seconds

The present invention can further form a zinc-nickel alloy plating layer on the cobalt-nickel alloy plating. The total amount of the zinc-nickel alloy plating layer is 150 to 500 µg / dm ² , and the proportion of nickel is 16 to 40 mass%. This has a role of a heat resistant antirust layer.

The conditions of zinc-nickel alloy plating are as follows.

(Zinc-Nickel Alloy Plating)

Zn: 0 to 30 g / ℓ

Ni: 0-25 g / ℓ

pH: 3? 4

Temperature: 40 ~ 50 ° C

Current density D _k : 0.5-5 A / dm ²

Time: 1 ~ 3 seconds

Thereafter, the following rust prevention treatment may be performed as necessary. Preferable antirust treatment is a coating treatment of chromium oxide alone or a mixture coating treatment of chromium oxide and zinc / zinc oxide. Coating of a mixture of chromium oxide and zinc / zinc oxide is a rust prevention layer of a zinc-chromium group mixture composed of zinc or zinc oxide and chromium oxide by electroplating using a zinc salt or a plating bath containing zinc oxide and chromate. It is a treatment to coat.

The plating bath is, typically, a _{K 2 Cr 2 O 7, Na} 2 Cr 2 O 7 It is at least one member and a water-soluble zinc salt such as ZnO, ZnSO _4? 7H ₂ O, etc. and at least one, a mixed aqueous solution of an alkali hydroxide, such as dichromate or CrO _3, such as is used. Examples of typical plating bath compositions and electrolytic conditions are as follows. The copper foil thus obtained has excellent heat resistance peeling strength, oxidation resistance and hydrochloric acid resistance.

(Chrome rust prevention treatment)

K ₂ Cr ₂ O ₇ (Na ₂ Cr ₂ O ₇ or CrO ₃ ): 2-10 g / ℓ

NaOH or KOH: 10-50 g / ℓ

? ZnO or _{ZnSO 4 7H 2 O:? 0.05} 10 g / ℓ

pH: 3? 13

Bath temperature: 20-80 ° C

Current density D _k : 0.05-5 A / dm ²

Time: 5-30 seconds

Anode: Pt-Ti plate, stainless steel plate, etc

As the amount of chromium oxide, a coating amount of 15 µg / dm ² or more and zinc of 30 µg / dm ² or more are required.

Finally, a silane treatment for applying a silane coupling agent to at least the roughened surface on the rust preventive layer is carried out with a focus on improving the adhesion between the copper foil and the resin substrate as necessary. As a silane coupling agent used for this silane treatment, an olefin silane, an epoxy silane, an acryl silane, an amino silane, a mercapto silane is mentioned, These can be selected suitably and can be used.

The coating method may be any of spraying with a silane coupling agent solution, coating with a coater, dipping, casting and the like. For example, Japanese Patent Application Laid-Open No. 60-15654 describes improving the adhesive force between copper foil and a resin substrate by performing chromate treatment on the rough surface side of copper foil and then performing a silane coupling agent treatment. See this for details. Then, annealing may be performed in order to improve the ductility of copper foil as needed.

Example

The following is a description based on examples and comparative examples. In addition, this embodiment is an example to the last, It is not limited only to this example. That is, the other aspect or modification contained in this invention is included.

The rolled copper alloy foil was subjected to a roughening treatment by copper-cobalt-nickel alloy plating in the conditions shown below, with 17 mg / dm ² of copper, 2000 μg / dm ^{2 of} cobalt, and 500 μg / dm ^{2 of} nickel. After washing with water, a cobalt-nickel alloy plating layer was formed thereon. In this case, the cobalt adhesion amount was 800 to 1400 µg / dm ² , and the nickel adhesion amount was 400 to 600 µg / dm ² . Furthermore, after forming a zinc-nickel alloy plating layer, the silane coupling agent was apply | coated and dried.

The bath composition and plating conditions used were as follows.

[Bath composition and plating conditions]

(1) Harmonic treatment (Cu-Co-Ni alloy plating)

Cu: 15 g / ℓ

Co: 8.5 g / ℓ

Ni: 8.6 g / ℓ

pH: 2.5

Temperature: 38 ° C.

Current density D _k : 20 A / dm ²

Time: 2 seconds

Copper deposition amount: 17 ㎎ / dm ²

Cobalt adhesion amount: 2000 ㎍ / dm ²

Nickel deposition amount: 500 ㎍ / dm ²

In the above conditions, when the three-dimensional surface area of the front and back surfaces measured with a laser microscope is set to (A), and the projected area when the three-dimensional surface area is measured is set to (B), ( When it is set as the calculated value (C) of A) / (B) = (C), let the three-dimensional surface area when the surface of the unannealed rolled copper foil and copper alloy foil be measured with the laser microscope be (A '). 1.0 when the projection area at the time of measuring the three-dimensional surface area is defined as (B '), and the calculated value (C') is calculated as (A ') / (B') = (C '). Copper foil for secondary battery negative electrode electrical power collectors in the range of <(C) / (C ') <1.1 was formed.

(Example 1)

In Example 1, the average surface roughness Ra by laser microscope measurement of both front and back sides is 0.07 micrometer, and the three-dimensional surface area at the time of measuring the surface of a roughening process surface with a laser microscope is made into (A), and the three-dimensional When the two-dimensional area of the projected area at the time of measuring the surface area is set to (B), when the calculated value (C) of (A) / (B) = (C) is set, unrolled rolled copper foil and copper alloy When the three-dimensional surface area when the surface of the foil is measured by a laser microscope is set to (A '), and the projection area when the three-dimensional surface area is measured is set to (B'), (A ') When setting it as the calculated value C 'of / (B') = (C '), (C) / (C') was 1.004.

The SEM photograph (20000 times) of a roughened particle in this case is shown in FIG. As shown in FIG. 1, fine and uniform particles were formed. Moreover, the average diameter of the roughening particle | grains of the roughening process surface was 0.1-0.4 micrometer, and the variation of the weight thickness was <0.5 ((sigma)).

Moreover, the cross section FIB-SIM photograph of a roughening particle layer is shown in FIG. As shown in FIG. 2, the maximum height of the roughening process layer was 0.2 micrometer, and was in the preferable range of 0.2 micrometer or less.

Moreover, the adhesiveness of an active material was investigated using this copper foil for secondary battery negative electrode electrical power collectors. First, a slurry was prepared by adding 11 wt% of polyvinylidene fluoride and 97 wt% of N-methyl-2-pyrrolidone as a thickener to artificial graphite as a negative electrode active material, respectively. The said slurry was apply | coated so that it might become a uniform thickness on the roughening process surface of the copper foil for negative electrode collectors using a doctor blade. After drying after press-molding, it cut into 1 cm width x 8 cm length, and produced the active material adhesive evaluation sample. Adhesive strength stuck the adhesive tape to the said sample, and measured the peeling strength at the time of peeling this adhesive tape to 90 degree directions. Secondary battery adhesiveness was favorable about evaluation of active material adhesiveness.

Moreover, the fall of roughening particle | grains (falling) was evaluated using this copper foil for secondary battery negative electrode electrical power collectors. For the fall evaluation, after the scotch tape is affixed to the roughened surface of the copper foil for negative electrode current collector and peeled, the scotch tape is discolored by adhering roughened particles on the adhesive surface of the scotch tape. The case where it cannot see is made into (circle). It was ○ about a fall evaluation. The results are shown in Table 1.

(Example 2)

In Example 2, the average surface roughness Ra by laser microscope measurement of both front and back surfaces is 0.07 micrometer, and the three-dimensional surface area at the time of measuring the surface of a roughening process surface with a laser microscope is made into (A), and the three-dimensional When the two-dimensional area of the projected area at the time of measuring the surface area is set to (B), when the calculated value (C) of (A) / (B) = (C) is set, unrolled rolled copper foil and copper alloy When the three-dimensional surface area when the surface of the foil is measured by a laser microscope is set to (A '), and the projection area when the three-dimensional surface area is measured is set to (B'), (A ') When setting it as the calculated value C 'of / (B') = (C '), (C) / (C') was 1.05.

Moreover, the average diameter of the roughening particle | grains of the roughening process surface was 0.1-0.4 micrometer, and the variation of the weight thickness was <0.5 ((sigma)). Moreover, the maximum height of the roughening process layer was 0.2 micrometer, and it existed in the preferable range of 0.2 micrometer or less. Moreover, when the adhesiveness of the active material was investigated using this copper foil for secondary battery negative electrode current collectors, the adhesiveness was good. Moreover, when the fall of the roughening process was investigated using this copper foil for secondary battery negative electrode electrical power collectors, the fall was (circle). This result is shown in Table 1 similarly.

(Example 3)

In Example 3, the average surface roughness Ra by the laser microscope measurement of the front and back both surfaces is 0.15 micrometer, and the three-dimensional surface area at the time of measuring the surface of a roughening process surface with a laser microscope is made into (A), and the three-dimensional When the two-dimensional area of the projected area at the time of measuring the surface area is set to (B), when the calculated value (C) of (A) / (B) = (C) is set, unrolled rolled copper foil and copper alloy When the three-dimensional surface area when the surface of the foil is measured by a laser microscope is set to (A '), and the two-dimensional area of the projection area when the three-dimensional surface area is measured as (B'), (A ') When setting it as the calculated value C 'of / (B') = (C '), (C) / (C') was 1.03.

Moreover, the average diameter of the roughening particle | grains of the roughening process surface was 0.1-0.4 micrometer, and the variation of the weight thickness was <0.5 ((sigma)). Moreover, the maximum height of the roughening process layer was 0.2 micrometer, and it existed in the preferable range of 0.2 micrometer or less. Moreover, when the adhesiveness of the active material was investigated using this copper foil for secondary battery negative electrode current collectors, the adhesiveness was good. Moreover, when the fall of the roughening process was investigated using this copper foil for secondary battery negative electrode electrical power collectors, the fall was (circle). This result is shown in Table 1 similarly.

Comparative Examples 1 and 2 were produced using copper sulfate plating conditions. Copper sulfate plating conditions are shown below.

Copper conditioning treatment

Cu: 10-25 g / ℓ

H ₂ SO ₄ : 20-100 g / ℓ

Temperature: 20? 40 ° C

D_k : 30-70 A / dm² 

Time: 1? 5 seconds

Furthermore, using the same plating conditions as the said Example, average surface roughness Ra by the laser microscope measurement of the front and back surfaces shown in the following comparative example 3 deviated from 0.04-0.20 micrometer, and also the surface of the roughening process surface When the three-dimensional surface area when measured with a laser microscope is set to (A), and the two-dimensional area of the projection area when the three-dimensional surface area is measured as (B), (A) / (B) = ( When it was set as the calculated value (C) of C), the three-dimensional surface area when the surface of the uncoated rolled copper foil and copper alloy foil was measured with the laser microscope was made into (A '), and the three-dimensional surface area was measured. When the projection area at the time is set to (B '), the calculated value (C') of (A ') / (B') = (C ') is 1.0 <(C) / (C'). ) Copper foil for secondary battery negative electrode electrical power collectors which deviate from the range of <1.1 was formed.

(Comparative Example 1)

In Comparative Example 1, the average surface roughness Ra by laser microscope measurement of both front and back sides was 0.61 µm, and the three-dimensional surface area when the surface of the roughened surface was measured with a laser microscope was defined as (A), and the three-dimensional surface was measured. When the two-dimensional area of the projected area at the time of measuring the surface area is set to (B), when the calculated value (C) of (A) / (B) = (C) is set, unrolled rolled copper foil and copper alloy When the three-dimensional surface area when the surface of the foil is measured by a laser microscope is set to (A '), and the projection area when the three-dimensional surface area is measured is set to (B'), (A ') (C) / (C ') was 1.38 when it was set as the calculated value (C') of / (B ') = (C'). These were all outside the scope of the present invention.

The SEM photograph (10000 times) of a roughened particle in this case is shown in FIG. As shown in this FIG. 3, coarse and nonuniform particles were formed. Moreover, the average diameter of the roughening particle | grains of the roughening process surface was 0.5-1.5 micrometers, and the deviation (sigma) of the weight thickness was 1.2.

Moreover, the maximum height of the roughening process layer was 3 micrometers, and was not in the preferable range of 0.2 micrometer or less. Moreover, when the adhesiveness of the active material was investigated using this copper foil for secondary battery negative electrode current collectors, the adhesiveness was poor. Moreover, when the fall of the roughening process was investigated using this copper foil for secondary battery negative electrode electrical power collectors, the fall was x. This result is shown in Table 1 similarly.

(Comparative Example 2)

In the comparative example 2, average surface roughness Ra by the laser microscope measurement of both front and back was 0.27 micrometer, and it was outside the range of this invention. In addition, when the three-dimensional surface area at the time of measuring the surface of a roughening process surface with a laser microscope is set to (A), and the projection area at the time of measuring the three-dimensional surface area is set to (B), (A When using the calculated value (C) of (C) of () / (B), the three-dimensional surface area at the time of measuring the surface of the unannealed rolled copper foil and copper alloy foil with a laser microscope is set to (A '), When the two-dimensional area of the projected area when the three-dimensional surface area is measured is set to (B '), the calculation value (C') of (A ') / (B') = (C ') is (C'). ) / (C ') was 1.15. This is beyond the scope of the present invention.

The roughened particles were coarse, and irregular particles were formed. Moreover, the average diameter of the roughening particle | grains of the roughening process surface was 0.5-1.5 micrometers, and the deviation (sigma) of the weight thickness was 0.7.

Moreover, the maximum height of the roughening process layer was 1.4 micrometers, and was not in the preferable range of 0.2 micrometer or less. Moreover, when the adhesiveness of the active material was investigated using this copper foil for secondary battery negative electrode current collectors, the adhesiveness was poor. Moreover, when the fall of the roughening process was investigated using this copper foil for secondary battery negative electrode electrical power collectors, the fall was (circle). This result is shown in Table 1 similarly.

(Comparative Example 3)

In the comparative example 3, average surface roughness Ra by the laser microscope measurement of both front and back was 0.27 micrometer, and it was outside the range of this invention. In addition, when the three-dimensional surface area at the time of measuring the surface of a roughening process surface with a laser microscope is set to (A), and the projection area at the time of measuring the three-dimensional surface area is set to (B), (A When using the calculated value (C) of (C) of () / (B), the three-dimensional surface area at the time of measuring the surface of the unannealed rolled copper foil and copper alloy foil with a laser microscope is set to (A '), When the two-dimensional area of the projected area when the three-dimensional surface area is measured is set to (B '), the calculation value (C') of (A ') / (B') = (C ') is (C'). ) / (C ') was 1.09. This is within the scope of the present invention.

The roughened particles had formed uniform particles. Moreover, the average diameter of the roughening particle | grains of the roughening process surface was 0.1-0.4 micrometer, and the deviation (sigma) of the weight thickness was 0.6.

Moreover, the maximum height of the roughening process layer was 1.0 micrometer, and was not in the preferable range of 0.2 micrometer or less. Moreover, when the adhesiveness of the active material was investigated using this copper foil for secondary battery negative electrode current collectors, the adhesiveness was poor. Moreover, when the fall of the roughening process was investigated using this copper foil for secondary battery negative electrode electrical power collectors, the fall was x. This result is shown in Table 1 similarly.

(Comparative Example 4)

When the roughening process is not performed about rolled copper foil, the example of (untreated) is shown. Roughness Ra is 0.05 micrometer and (C) / (C ') is 1. As shown in Table 1, the adhesiveness in this case was incapable of measuring and was inferior. As a state of this rolled copper foil, it turns out that it is not suitable as a material which improves the adhesiveness of a secondary battery active material.

Industrial availability

This invention is excellent in the adhesiveness of a secondary battery active material, and has the outstanding effect which can reduce the dispersion | variation in the weight thickness of a secondary battery active material, Furthermore, since it is excellent also in weather resistance and heat resistance, copper foil for secondary battery negative electrode electrical power collectors It is useful as.

Claims (6)

As a copper foil which performed the roughening process to both front and back of rolled copper alloy foil, the projection area when the three-dimensional surface area when measured with the laser microscope of the said front and back both sides is set to (A), and the three-dimensional surface area is measured. When the two-dimensional area was set to (B), when the calculated value (C) of (A) / (B) = (C) was used, the surface of the uncoated rolled copper foil and the copper alloy foil was measured by a laser microscope. When the three-dimensional surface area at the time is (A ') and the projected area two-dimensional area at the time of measuring the three-dimensional surface area is (B'), (A ') / (B') = (C ' When it is set as the calculated value (C '), it is the range of 1.0 <(C) / (C') <1.1, The copper foil for secondary battery negative electrode electrical power collectors characterized by the above-mentioned. The method of claim 1,
The average diameter of the roughening particle | grains of a roughening process surface is 0.1-0.4 micrometers, Copper foil for secondary battery negative electrode electrical power collectors characterized by the above-mentioned. The method according to claim 1 or 2,
The maximum height of a roughening process layer is 0.2 micrometer or less, Copper foil for secondary battery negative electrode electrical power collectors characterized by the above-mentioned. The method according to any one of claims 1 to 3,
The roughening particle | grains are formed in the front and back surfaces of a rolled copper foil and a copper alloy foil by 1 type of plating of copper, cobalt, nickel, or these 2 or more types of alloy plating, The copper foil for secondary battery negative electrode electrical power collectors characterized by the above-mentioned. The method according to any one of claims 1 to 4,
On the roughened surface of the front and back surfaces of the rolled copper foil and the copper alloy foil, at least one antirust treatment layer or heat resistant layer selected from a cobalt-nickel alloy plating layer, a zinc-nickel alloy plating layer, and a chromate layer, and / or a silane coupling layer Copper foil for secondary battery negative electrode electrical power collectors which have it. 6. The method according to any one of claims 1 to 5,
The weight thickness deviation (sigma) of the copper foil width direction of the rolled copper foil and copper alloy foil after front-back both-side roughening process is 0.5 or less, The copper foil for secondary battery negative electrode collectors characterized by the above-mentioned.

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